1. Field of the Invention
The present invention relates to a method of manufacturing a substrate for displays and a substrate for displays manufactured by the same method, and more particularly, to a method of manufacturing a substrate for displays, which has a film formed thereon to prevent electrification of the substrate surface, and a substrate for displays manufactured by the same method.
2. Prior Art
Conventional substrates for displays for use in field emission displays (FED) including surface-conduction electron-emitter devices (SED), and plasma display panels (PDP) had the disadvantage that the substrate surface is prone to electrification attributable to the driving method of the FED or PDP, i.e., due to application of a high electric field between the substrates for generation of light or due to exposure of the surface of the substrate to plasma. The electrification can cause generation of a spark, leading to a shortened service life of a display element. The electrification of the substrate surface depends on the surface electrical resistance of the substrate.
To prevent the shortening of the life of the display element caused by electrification of the substrate surface, it has been proposed to form, on a surface of the substrate, a thin film of a metal oxynitride having a surface electrical resistance controlled to a desired value suitable for anti-electrification. The formation of the thin film of the metal oxynitride on the surface of the substrate is performed by sputtering using a metal target in a mixture gas atmosphere of oxygen and nitrogen. The surface electrical resistance of the thin film is controlled to a desired value by changing the mixing ratio of oxygen and nitrogen in the mixture gas atmosphere.
According to the conventional anti-electrification method, however, it was difficult to control the surface electrical resistance to a desired value because when the ratio of oxygen and nitrogen in the mixture gas atmosphere is changed during sputtering using the metal target, the surface electrical resistance of the thin film to be formed on the surface of the substrate changes drastically even with a small change in the mixing ratio of oxygen and nitrogen.
It is therefore an object of the present invention to provide a method of manufacturing a substrate for displays, which can easily control the surface electrical resistance of the anti-electrification film formed on a surface of the substrate, and a substrate for displays manufactured by the same method.
To attain the above object, the present invention provides a method of manufacturing a substrate for displays, comprising the steps of preparing a target from a metal oxide, and forming a thin film of a metal oxynitride on a surface of the substrate by sputtering using the target in an atmosphere of a mixture gas of an inert gas and nitrogen, a mixing ratio of the inert gas and nitrogen in the atmosphere being adjusted such that the thin film has a desired surface electrical resistance.
According to the method of the present invention, it is possible to easily control the value of the surface electrical resistance of the anti-electrification thin film formed on the surface of the substrate to a desired value.
Preferably, the inert gas is contained in the atmosphere in an amount of 5 to 95 volume %.
As a result, it is possible to form an anti-electrification thin film of metal oxynitride on the surface of the substrate in a reliable and a highly reproducible manner, thereby making it possible to positively control the value of the surface electrical resistance of the thin film to a desired value.
Preferably, the desired surface electrical resistance is 1.0xc3x97108 to 1.0xc3x971012 xcexa9/xe2x96xa1.
As a result, electric charges of the surface of the substrate can be dissipated, thereby making it possible to suppress the shortening of the life of the display element due to electrification of the substrate surface, that is, the element can fully withstand practical use.
In a preferred form of the present invention, the target is formed of at least two kinds of metal oxides.
As a result, it is possible to control the surface electrical resistance value of the thin film to a desired value in a more reliable manner.
Preferably, one kind of the two kinds of metal oxides is an oxide of an element selected from the group consisting of titanium and zirconium.
Preferably, the other kind of the two kinds of metal oxides is an oxide of an element selected from the group consisting of niobium, vanadium, tantalum, yttrium, and tungsten.
Preferably, one kind of the two kinds of metal oxides is contained in the target in an amount of 70 to 99.5 weight %.
Still preferably, the other kind of the two kinds of metal oxides is contained in the target in an amount of 0.5 to 30 weight %.
As a result, it is possible to control the surface electrical resistance of the thin film in a more reliable manner.
In another preferred form of the present invention, the method of manufacturing a substrate for displays further comprises the step of forming at least one anti-movable ion thermodiffusion film stacked on the thin film formed on the surface of the substrate.
As a result, it is possible to prevent electrification of the substrate surface, as well as prevent abnormal operation of the display element due to thermodiffusion of movable ions.
Preferably, the anti-movable ion thermodiffusion film is formed of a compound selected from the group consisting of an oxide of silicon, an oxynitride of silicon, or a nitride of silicon.
As a result, it is possible to positively prevent abnormal operation of the display element due to thermodiffusion of movable ions.
Preferably, the anti-movable ion thermodiffusion film has a total film thickness of 20 to 1000 nm.
As a result, it is possible to effectively prevent abnormal operation of the display element due to thermodiffusion of movable ions.
Further, the present invention provides a substrate for displays manufactured by preparing a target from a metal oxide, and forming a thin film of a metal oxynitride on a surface of the substrate by sputtering using the target in an atmosphere of a mixture gas of an inert gas and nitrogen, a mixing ratio of said inert gas and nitrogen in said atmosphere being adjusted such that said thin film has a desired surface electrical resistance.
According to the substrate for displays of the present invention, no electrification of the substrate surface can occur, making it possible to obtain a substrate for displays at a low cost without shortening of the life of the display element.
The above and other objects, features and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.